Add reST target for Doc/packaging/setupcfg
diff --git a/Doc/packaging/setupcfg.rst b/Doc/packaging/setupcfg.rst
index 68786b2..9af8b63 100644
--- a/Doc/packaging/setupcfg.rst
+++ b/Doc/packaging/setupcfg.rst
@@ -1,5 +1,7 @@
 .. highlightlang:: cfg
 
+.. _packaging-setupcfg:
+
 *******************************************
 Specification of the :file:`setup.cfg` file
 *******************************************